I'm sorry saying this, but the only good thing of this plugin is the idea behind it.

I was firstly managing my Jenkins users authorizations with the Role-based Authorization Strategy plugin. At a certain point, I have created Folders onto my Jenkins Controller, so, I needed to have a plugin that could manage roles based on Folders, I have then installed this plugin.

From Manage Jenkins -> Security (Folder-based Authorization plugin documentation still has the old name "Configure Global Security") I have selected the Folder-based Authorization and saved.
1. This completely wiped out my old Role-based Authorization configuration, without warning me of the behavior

Once on the Folder-based Authorization plugin UI (I at last expected it to inherit the old Authorization strategy of the Jenkins Controller, but it didn't)...

2. The text-box made to select permissions (like Build/Read, etc.) was so tiny, it could neither be enlarged

3. The permissions had to be selected one at a time while keeping Ctrl pressed

4. The button "Add Role" neither worked at all

I understand that somethings expect feedbacks to improve in time, but they should not damage nothing, in this case my old Role-based Authorization strategies wiped out.